The present invention relates to a printing/coating method and apparatus which cure ink or varnish, transferred onto a transfer object, using light emitted by a light source.
A printing/coating method which prints or coats a sheet serving as a transfer object using ultraviolet curing ink or varnish and irradiates the sheet with ultraviolet rays from a UV lamp to cure the ultraviolet curing ink/varnish has conventionally been proposed, as disclosed in Japanese Patent Laid-Open No. 54-123305.
Light curing ink which contains a photopolymerization initiator and starts to cure upon being irradiated with light such as ultraviolet rays has also been proposed, as disclosed in Japanese Patent Laid-Open No. 2009-221441.
On the other hand, in recent years, a printing/coating method which attains both energy saving and a low environmental load has been developed. According to this technique, ultraviolet curing ink/varnish is cured using a light-emitting diode (LED-UV) which emits light with UV wavelengths in place of a conventional UV lamp, as disclosed in Japanese Patent Laid-Open No. 2008-307891.
In the above-mentioned conventional printing/coating methods, because light emitted by LED-UV has an extremely narrow wavelength range (e.g., 370 nm to 380 nm), only ink/varnish which reacts to light in a narrow wavelength range can be used as the ink/varnish which cures with light from LED-UV.